Throughout this specification the words "roof bolt" and derivations of these words are taken to include other strata stabilisation articles and other similar named bolting articles such as rock bolts, anchor bolts, anchor tendons, tendons and any other similar articles which can be used for any purpose including drilling and bolting of ribs, floors, walls and faces of mines and any other location requiring strata stabilisation.
The expression "roof bolt installation apparatus" when used in this specification and claims means an apparatus able to be predominantly used for roof bolting processes, but is also able to be used exclusively for drilling or coring purposes, without any actual installation of roof bolts. In which latter case the drilling unit, timber jack component and other components are simply used for drilling and or coring purposes alone.
Prior art roof bolt installation apparatus also known as roof bolters, generally have a timber jack which is constructed from a structural member sliding in another structural member. The sliding mechanism is generally achieved by the attachment of similarly shaped angled rails to each structural member. These rails are attached along the longitudinal length of the structural members so that one structural member can extend from a compacted or retracted height to approximately 1.75 times the compacted or retracted height. Such a timber jack braces the roof bolter so that a drilling unit can first drill a surface and then install a roof bolt.
Mounted on a base portion of the timber jack is a feed unit which slides relative to the base portion. On the feed unit is mounted the drilling unit which slides thereon. The sliding action is also produced and guided by means of similarly constructed externally mounted rails on the structural members and on corresponding portions of the feed unit so that the feed unit can slide relative to the base of the timber jack.
The sliding surfaces deteriorate relatively quickkly in service because during the life of a roof bolt installation apparatus it is deluged with water and coal, sandstone, rock and minerals which fall On the rails causing wear of the rails. Such wear occurs at an accelerated rate.
This wear damages the rails and can prematurely make the roof bolt installation apparatus inoperable because of potential misalignment of the respective sliding frames. This condition also means that the apparatus is prematurely withdrawn from service. Alignment is important when drilling is required into rock surfaces to ensure that a roof bolt will follow the same path as a drill rod which has gone before it to excavate the hole into which the roof bolt will be situated. Such alignment is also needed to ensure that the drill rod will make contact with a rock surface and not other portions of the roof bolter.
It is an object of the invention to provide a roof bolt installation apparatus which ameliorates, at least in part, at least one of the disadvantages of the prior art.